Smart card having additional connector pads

ABSTRACT

A smart card, having a set of standardized contact pads and an additional set of contact pads to provide additional performance characteristics. The additional contact pads are formed on the smart card on the area located between the ISO 7816 standardized contact pads C 1  through C 4  and C 5  through C 8 , which area was previously used solely as a ground plane connection to contact pad C 5 . By increasing the number of contact pads, the additional pads can be used for input/output connections, memory, flash memory and/or interfaces with specific functions such as a service provided interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of 09/993,810 filed Nov. 6, 2001, nowU.S. Pat. No. 6,634,565.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

(Not Applicable)

BACKGROUND OF THE INVENTION

The present invention relates generally to electronic devices, and moreparticularly to an electronic integrated circuit card, i.e., smart card,that provides additional electrical connectors or contact pads, so as toprovide additional functional capability, speed and/or larger memorycapacity for the smart card.

The typical prior art smart card contains an integrating circuitprocessor, a small amount of memory, and an interface circuit. Typicalapplications of prior art smart cards include telephone calling cardsand stored value cards. More recently, smart cards have been utilized tocontrol access of users to various systems such as banking, internet orother electronic security systems.

Currently, most prior art smart cards are fabricated in accordance withan international standard, namely the International StandardOrganization/International Electrotechnical Commission (ISO) 7816standard. As is well known, in the ISO 7816 standard a card reader isemployed to interface between the smart card and a host computer. Thecard reader communicates with the smart card in accordance with the ISO7816 standard, and communicates with the host computer via an interfacesuch as a RS-232, a PS/2 or a universal serial bus (USB). One example ofa specialized prior art smart card and card reader and its communicationprotocol with a host computer is disclosed in United States LettersPatent No. 6,168,077 entitled Apparatus and Method of Providing a DualMode Card and Reader issued Jan. 2, 2001 assigned to Litronic, Inc., theAssignee of the subject application, the disclosure of which isexpressly incorporated herein by reference.

The ISO 7816 standard specifies the dimensions, locations and assignmentfor each of the electrical contacts or contact zones formed on the smartcard which then interface with conventional smart card readers. Theplural contact zones or pads are designated by the ISO 7816 standard aszones or pads C1 through C8. The pads C1 through C4 are separated by acentral region on the card from pads C5 through C8. This void or centralregion has heretofore been utilized to facilitate the mounting of theintegrated circuit die with the integrated circuit die being attached onone side of the carrier while the contact pads C1 through C8 beingformed and disposed on the opposite side of the carrier. The integratedcircuit die has hereto been electrically connected to the contact padsC1 through C8 via conventional bonding wiring techniques which requirethat the central area of the carrier existing between the contact padsC1 through C8 be connected to ground via contact pad C5. As a result,the entire central region or portion of the carrier located between thecontact pads C1 through C4 and C5 through C8 has not been available foradditional contact pads, but rather has been used solely to providemounting of the integrated circuit die to the smart card.

In view of the above, the number of connector zones to the smart cardhave been limited to the zones C1 through C8 which, as will be explainedin more detail infra, serves to limit the function and memory of priorart smart cards.

As such, there exists a substantial need in the art to provideadditional conductive pads on a conventional smart card in conformitywith the ISO 7816 standard which enables such additional contact pads tobe utilized for additional purposes such as to enable greater memory,communications, processing speeds and the like.

SUMMARY OF THE INVENTION

The present invention specifically addresses and alleviates theabove-referenced deficiencies in the prior art. More particularly, thepresent invention contemplates the use of additional contact pads beingformed on the smart card in the area located between the contact pads C1through C4 and C5 through C8, which space heretofore has been usedsolely as a ground plane connected to contact pad C5. By increasing thenumber of contact pads, the additional pads can be used for numerousdesired purposes such as input/output connections, memory and/orinterfaces with specific functions, such as Serial Peripheral Interface(SPI).

To increase the number of contact pads, the present invention utilizes aflip chip package mounting technique for the integrated circuitprocessor which replaces the conventional prior art wire bonding diemounting technique. In the present invention, the integrated circuitflip chip is formed with an array of solder bumps or solder balls on oneside thereof. The flip chip is mounted on a printed circuit board withthe solder bumps connected to a printed circuit formed on the printedcircuit board. Through vias formed in the printed circuit board, theflip chip pads and solder bumps are electrically connected to thecontact pads formed on the opposing surface of the printed circuitboard. Since the electrical connections between the flip chip and thecontact pads is facilitated by the traces of the printed circuit board,which can be located beneath the flip chip (as opposed to only on theperiphery thereof), the central area of the printed circuit is now freeto include additional contact pads thereon. As a result, in addition tothe contact pads standardized by ISO 7816, additional contact pads areprovided which facilitate additional functions and/or interfaces to thesmart card integrated circuit.

Preferably, the smart card connectors or pads provided by the presentinvention comprise the eight ISO 7816 standardized contact pads C1through C8 and an additional five contact pads designated C9 to C13which are available for more connections as desired. However, thoseskilled in the art will recognize that the number of additional contactpads may be varied as desired.

By use of the additional contact pads formed in the present invention,the integrated circuit and the functionality of the smart card can besignificantly enhanced, for instance, incorporating differingcommunication ports, such as USB, SPI and SMB (System Management Bus)ports that communicates with devices in the reader such as serial memoryand a real-time clock.

In one embodiment of the present invention, to communicate with thesmart card, a conventional card reader can be modified with moreconnectors corresponding to the additional contact pads on the smartcard that communicate with circuitry on the reader. Alternatively, twoadditional contact modules can be embedded in one smart card.Interconnects are formed to establish a mutual communication betweenthese two die modules via circuitry in the reader.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings wherein:

FIG. 1 is a top plan view showing the standardized ISO 7816 connectorpattern of a prior art smart card;

FIG. 2 is an enlarged partial view of the smart card illustrated as FIG.1 depicting the location and size of the conducting pads/zones C1through C8;

FIG. 3 is a side view illustrating the prior art wire bonding mountingof the integrated circuit die into the smart card of FIG. 1;

FIG. 4 illustrates the present invention's flip chip mounting of theintegrated circuit flip chip into the smart card body;

FIG. 5 comprises a plan view of the connector pattern of the presentinvention formed on the contact side of the printed circuit board of thesmart card of the invention;

FIG. 6 comprises a plan view of the bonding side of the printed circuitboard of the smart card of the present invention.

FIG. 7 depicts a specific application for SPI of the smart card of thepresent invention; and

FIG. 8 shows a dual die module smart card of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 and FIG. 2 depict a conventional prior smart card 10. Asspecified by the ISO 7816 standard, the smart card has a specificconnector/pad or zone pattern with eight flat contact pads designatedC1-C8 formed on a carrier disposed within the smart card 10. The contactassignment for these contact pads is standardized as follows: Thecontact pad C1 is connected to a supplied voltage VCC. The contact padC2 is assigned for a reset signal (RST). The contact pad C3 is assignedfor a clock signal CLK. The contact pad C4 is reserved for future use inother parts of ISO/IEC 7816. The contact pad C5 is grounded (GND). Thecontact pad C6 is assigned for variable supply voltage, that is, theprogramming voltage VPP. The contact pad C7 is an input/output (I/O) padfor data input/output. The contact pad C8 is also reserved for futureuse in other pads of ISO/IEC 7816.

As shown in FIG. 2, the center portion 12 of the carrier is typicallyelectrically connected to the contact pad C5. In the prior art, thiscenter portion 12 is used to mount the smart card integrated circuitchip or die (with pads pointing up and away from the ground plane) via aconventional wire bonding packaging technique. The specifics of theconventional wire bonding packing technique are illustrated in FIG. 3.As shown, the card blank 30 of the smart card 10 is milled to form acavity 31 to accommodate the integrated circuit die 32. The integratedcircuit die 32 is mounted on a carrier 34, typically comprising a thinfilm printed circuit board. The central portion of the carrier 34 isthus occupied by the integrated circuit die 32. Bonding wires 36 areformed to electrically connect the respective pads on the integratedcircuit die 32 to the carrier 34 peripheral to the integrated circuitdie 32. As a result, peripheral contact pads CX (C1-C8) are formed toroute the pads of the integrated circuit die 32 through vias 38 formedin the carrier 34. As the center portion 12 of the carrier 34 isoccupied by mounting the integrated circuit chip 36, the connectors(contact pads CX) can only be arranged on the periphery of the die 32and card blank 30, thus leaving the central portion typically beingconnected to the ground pad C5.

Due to the integrated circuit chip or die 36 occupying the centerportion 12, the ISO 7816 standard only utilizes connector pads C1through C4 and C5 through C8 for various assignments as previouslymentioned. Thus, with the standardized prior art ISO 7816 configuration,the prior art smart card 10 normally incorporates only an 8 bytemicroprocessor, a 256-byte SRAM, a 48K-byte ROM and a 16K-byte EEPROM tooperate with the frequency of about 3.579 MHz and having only an ISIserial port. As such, improved operational function, communication andspeed of the prior art smart card 10 has been limited.

In contrast to the prior art, the present invention specificallyutilizes a flip chip mounting technique for the integrated circuit whichallows the central portion 12 of the smart card 10 a to be utilized foradditional pad connectors.

Referring more particularly to FIGS. 4, 5 and 6, the particular flipchip mounting technique utilized in the present invention is depicted.As in the prior art, a cavity 31 a is formed in the smart card blank 30a and a printed circuit board 38 a is mounted therein, preferablyfabricated from a thin film. Utilizing conventional printed circuitboard fabrication technology, plural electrical contact pads CX (C1through C8) are formed on the contact side surface of the circuit boardas depicted in FIG. 5, which pads C1 through C8 are formed in exactconformity with the ISO 7816 standard. However, as shown in FIG. 5, thecontact side of the printed circuit board 38 a of the present inventionadditionally defines preferably five additional connector pads CAdesignated individually in FIG. 5 as C9, C10, C11, C12 and C13. Each ofthe connector pads C1 through C13 include a via 40 which extends throughthe circuit board 38 a from the contact side to the opposite bondingside of the printed circuit board.

The opposite bonding side of the circuit board 38 a is depicted in FIG.6. The bonding side includes suitable printed circuit board tracing 42which extend from each of the vias 40 to mounting pad locations for theintegrated circuit flip chip 50. Although differing flip chip processors50 are contemplated in the present invention, in the preferredembodiment, a nimbus brand flip chip manufactured by Atmel of San Jose,Calif. is utilized. As is known and shown in FIG. 4, the flip chip 50includes plural solder bumps 44 at mounting pad locations which areutilized for mounting and forming electrical connections through theplural vias 40 to each of the mounting pads C1 through C13. Since theprinted circuit board tracings 42 can be routed upon the bonding side ofthe printed circuit board to all vias (even those located under the flipchip 50), the previously unused central portion of the printed circuitboard can now serve to provide additional electrical connections todesired connections for the integrated circuit die. In this matter, thecentral portion of the printed circuit board 38 a is thereby freed inthe present invention to accommodate the additional electrical padconnections C9 through C13 to provide additional input/outputconnections and communication connections to the smart card withoutincreasing the overall contact size as defined by the ISO 7816 standard.

As best shown in FIG. 7, the conventional connector pads C1 through C8can be utilized for the same assignments as defined in the ISO 7816standard. However, the additional connector pads C9 through C13 can beutilized for various purposes. FIG. 7 depicts a preferred designationespecially suitable for SPI applications. As shown in FIG. 7, thecontact pad C1 is assigned for the power supply VCC, the contact pad C2is assigned for the reset signal RST, the contact pad C3 is assigned,for the clock signal, the contact pad C5 is connected to the ground, andthe contact pad C6 is assigned for the USB clock signal (USBCLK, theprogram voltage supply VPP). The contact pad C7 is assigned for ISOinput/output. The contact pad C4 and C8 which were previously reservedand unused can now be assigned for USB to connect a PC, a work stationor other electronic apparatus. The contact pad C9 can be assigned forSPI input. The contact pad C10 can be assigned for SPI output. Thecontact pad C1 may be assigned for SPI clock signal and the contact padC12 and C13 may be assigned for select signals SPISEL.

By such an arrangement, the smart card 10 a of the present inventionachieves substantial improved functionality having, for instance, a32-byte microprocessor, 5K-byte SRAM, 96K-byte ROM, 64K-byte EEPROM andoperating with a frequency of 16 MHz having an ISO port, a high speedUSB port, a serial interface port and an SMB port. As such, by way ofthe present invention, increased performance for the smart card 10 a isachieved.

Those skilled in the art will recognize that the smart card of thepresent invention can be utilized in conventional smart card readershaving conventional spring contacts corresponding to pads C1 through C8in a manner heretofore utilized in the prior art. However, suchconventional card readers can additionally be easily modified to includeadditional corresponding spring contacts to register and interface withthe additional connector pads C9 and C13 such that same can be utilizedas desired.

FIG. 8 shows an additional embodiment of the present invention whereinthe smart card 80 includes two integrated circuit modules 81 and 82embedded therein. The integrated circuit die 81 has both thestandardized connector pads C1 through C8 and the additional connectorpads C9 through C13 as described above. The integrated circuit module 82includes only the standardized connectors C1 through C8. Electricalconnections between the modules 81 and 82 are achieved usingconventional PCB interconnection on the smart card.

After inserting the smart card 80 into a prior art card reader, only theconnectors C1 through C8 of the integrated circuit die 82 are in directcontact with the reader. That is, a direct communication is onlyestablished between the card reader and the module 82. The communicationfor the module 81 is established indirectly via the interconnect coupledto the integrated circuit module 82. In this manner, conventional cardreaders can be utilized to read the module 81 embedded in the smart card80. It will be appreciated that the number of the modules 81 in thesmart card 80 is not limited to one only. One of ordinary skill in theart may modify the embodiment by embedding more than one module 81 inthe same smart card to obtain more functionalities.

Those skilled in the art will appreciate that the particular assignmentsmade for the additional connector pads C9 and C13 are illustrated inFIG. 7 is solely for illustration purposes and comprise only one of avariety of connector pad assignments for the smart card of the presentinvention. In other applications, the connector pads C9 through C13 maybe assigned to facilitate completely different functions, such asinput/output, flash memory or the like, to be capable of accommodatingspecific operational requirements.

Indeed, each of the features and embodiments described herein can beused by itself, or in combination with one or more of other features andembodiment. Thus, the invention is not limited by the illustratedembodiment but is to be defined by the following claims when read in thebroadest reasonable manner to preserve the validity of

What is claimed is:
 1. A smart card for communicating with a cardreader, comprising: a card body, milled with a cavity; an integratedcircuit, disposed in the cavity of the card body; a printed circuitboard, having a first side bonded with the integrated circuit by aplurality of solder bumps, and an opposite second side facing upwardlyfrom said cavity; and a plurality of contact pads formed on said secondside of the printed circuit board, through which electrical connectionsfrom the integrated circuit die to the card reader is establish; whereinthe contact pads comprising eight ISO 7816 standardized contact pads anda plurality of additional contact pads between the ISO 7816 standardizedcontact pads.
 2. A smart card, comprising: a card body; a first diemodule embedded in the card body with a plurality of first contact pads;and a second die module embedded in the card body with at least thefirst contact pads, wherein the first die module is electricallyconnected directly to the second die module.
 3. The smart card accordingto claim 2, wherein the first contact pads include eight standardizedcontact pads and the second die module further includes a plurality ofadditional I/O connection pads.
 4. The smart card according to claim 3,wherein the first contact pads of the first and second die module aresized and configured in conformity with the ISO 7816 standard.
 5. Thesmart card according to claim 4, wherein the second die module comprisesfive additional I/O connection pads between the first contact pads.